In the manufacture of standard concrete monuments to define survey positions, what is the correct concrete mix by parts of Cement, Sand, and Gravel?

• A. Cement 1 part; Sand 1 part; Gravel 2 parts
• B. Cement 2 parts; Sand 2 parts; Gravel 4 parts
• C. Cement 1 part; Sand 2 parts; Gravel 4 parts
• D. Cement 1 part; Sand 3 parts; Gravel 5 parts

Answer: (C)

This item tests selecting a standard concrete mix proportion used for durable survey monuments. For field monument work, a common nominal mix is cement 1 part, sand 2 parts, and gravel 4 parts. This 1:2:4 ratio provides a good balance of workability, strength, and economy, giving enough cement to bind the aggregates while keeping the mix dense and durable against weathering and ground conditions. A mix with more cement would be unnecessary and more costly, and a mix with less cement would be weaker and less durable for monument stability. A leaner mix with even less cement would also reduce density and long-term performance. Hence, 1 part cement, 2 parts sand, and 4 parts gravel is the appropriate choice.